Orthodontic systems typically use round archwire connected to brackets and anchored in buccal tubes on molars or non-round archwires generally of rectangular cross section connected to brackets and anchored in buccal tubes. Round wire is generally used in the Begg technique, and rectangular wire is generally used in the edgewise technique. When round wire is used, it is not used for torquing, while rectangular wire can be used for applying torquing forces.
At some stage in the edgewise technique, it is advantageous to use round wire with edgewise brackets for accomplishing certain movements not concerned with torquing; thereafter, it is advantageous to use rectangular archwire where torquing is needed to accomplish certain teeth movement. Where round archwire is first used in an edgewise system, it would require the use of a buccal tube having a round opening, and when it is then desired to apply torquing forces, it is necessary to use a buccal tube having a rectangular opening. One method of handling both wires is to first mount round buccal tubes on the molars, and thereafter replace them with rectangular buccal tubes which requires considerable time of the orthodontist in the changeover process. More often, a double tube appliance having both round and rectangular tubes on the one base is used to avoid the need for a changeover. Such an appliance is bulky, and depending upon the arrangement of the tubes, they may protrude into the check or into the gingiva. Further, such an appliance may be subject to damaging occlusion forces and always requires archwire bending which is intended to be avoided by the straight wire technique.
It has been known to use buccal tube assemblies that are capable of accommodating round wire or doubled back wire forms, such as in U.S. Pat. No. 3,526,961. This patent predates the development of techniques used today where both round and rectangular wires are used over the complete treatment of a patient. There is now a need for facilitating the changing from round archwire use to rectangular archwire use.